‘Huge’ quake alert in Japan

Officials in Japan have warned of an increased risk of a “huge” earthquake in the next week after a 7.7-magnitude quake struck off the country’s north-east coast.

Thousands of people were told to leave coastal areas for higher ground after the quake in waters off Iwate prefecture, 530km north of Tokyo.

While the biggest waves measured around 80cm, the meteorological agency warns quakes “causing even stronger shaking” could occur in the next week. It later warned the risk of one measuring 8.0 or higher was now “relatively higher than during normal times”.

Tremors were felt as far away as the capital city and in Hokkaido tsunami alerts remained in place two hours after the quake struck at 4.52pm local time on April 20.

Cabinet Secretary Minoru Kihara, pictured, told media there were no immediate reports of major damage or injuries.

A tsunami warning was issued across part of Japan’s east coast. It was the second-highest of three levels, with people being told to evacuate immediately from coastal and riverside areas and move to higher ground or an evacuation building.

It was later downgraded to a tsunami alert before being removed entirely shortly before midnight local time.

Japan’s location on the Ring of Fire means it has about 1,500 earthquakes per annum. It accounts for 10 per cent of quakes measuring 6.0 magnitude or higher globally.

In March 2011, the country was hit by the devastating 9.0-magnitude quake off the coast to the south of Iwate province, the most powerful earthquake it has ever recorded.

The meltdown at Fukushima was one of the worst nuclear disasters in history. Since then, the government issues warnings and advisories for people to get to higher ground.

The seismic intensity and epicentre of the earthquake on April 20 are shown on a weather agency map, below.